Process for converting cellulose

ABSTRACT

A process for converting cellulose to a normally liquid oil, which includes contacting cellulose with water, a reducing gas and a catalytic compound containing a sulfur component and an alkali metal or ammonium ion component at particular conditions of temperature and pressure to insure a liquid water phase at conversion conditions employed. The reducing gas may be carbon monoxide, hydrogen, or a mixture thereof.

United States Patent 11 1 1111 3,864,097

Urban 1 Feb. 4, 1975 PROCESS FOR CONVERTING CELLULOSE 2,016,170 10/1935Mallett 44/50 x Inventor: Peer Urban, Northbrook 111. 2,246,973 6/1941Camilli et a1. 44/62 X [73] Assignee: Universal Oil Products Company,Primary ExaminerPaul F. Shaver Des Plaines,-ll1. Attorney, Agent, orFirmlames R. Hoatson, Jr.; [22] Filed: Jam 15, 1973 Thomas K. McBride;William H. Page, II

[21] Appl. No.: 323,615 [57] ABSTRACT A process for converting celluloseto a normally liquid [52] U.S. Cl 44/50, 44/62, 201/25 oil, whichincludes contacting cellulose with water, a [51] Int. Cl. C10j 1/00reducing g and a catalytic compound containing a [58] Field of Search44/50, 62; 201/25 sulfur component and an alkali metal or ammonium ioncomponent at particular conditions of temperature [5 6] References Citedand pressure to insure a liquid water phase at conver- UNITED STATESPATENTS sion conditions employed. The reducing gas may be 276 981 5/1883Pradon 44/62 carbon monoxide, hydrogen, or a mixture thereof. 1,889Z83612/1932 Lowry et al 44/62 8 Claims, N0 Drawings l PROCESS FOR CONVERTINGCELLULOSE BACKGROUND OF INVENTION This invention relates to a processfor converting cellulose to a hydrocarbonaceous, normally liquid oil.

This invention also relates to a process for converting municipal wastematerials into valuable hydrocarbonaceous compounds.

It is known that cellulose can be converted into a hydrocarbonaceous tarby treatment with water and carbon monoxide at elevated temperatures andpressures. The conversion of cellulose to a hydrocarbonaceous liquid isadvantageous in two aspects in particular. First, this type ofconversion provides a method for reducing the volume of the enormousamount of municipal refuse which is normally buried or burned in orderto effect disposal. Further, burning and/or burying refuse is wastefulof the hydrocarbonaceous material, primarily in the form of cellulose,which are present in such refuse. By converting the cellulose componentsof typical municipal waste matter into valuable liquid hydrocarbonaceousproducts, the volume of the refuse can be diminished by as much as 90%.The hydrocarbonaceous liquid products recovered may be employed as fuelor as feed stocks in processes for producing chemical derivatives.Previously disclosed methods for converting cellulose using water and areducing gas are able to achieve only undesirably low rates ofconversion. Prior art methods are hampered in that hydrogen has beenfound inactive when used as the reducing gas in place of carbonmonoxide, whereas carbon monoxide is an expensive reducing gas relativeto a carbon monoxide-hydrogen mixture such as synthesis gas.

SUMMARY OF INVENTION An object of the present invention is to provide aprocess for converting cellulose to normally liquid hydrocarbonaceousmaterial. Another object of the present invention is to provide aprocess for reducing the volume of cellulose-containing municipalrefuse. A further object of the present invention is to provide aprocess for converting cellulose to a hydrocarbonaceous liquid utilizinga compound containing a sulfur component and an alkali metal or ammoniumion component as a catalyst.

Another object of the present invention is to provide a process forconverting cellulose to a hydrocarbonaceous liquid, utilizing hydrogenor a mixture thereof with carbon monoxide as a reducing gas, whichprovides a conversion equally as good as the conversion obtainedutilizing carbon monoxide alone as the reducing gas in the conversionoperation.

In an embodiment, the present invention relates to a process forconverting cellulose to a normally liquid hydrocarbonaceous productwhich comprises contacting the cellulose with water, a reducing gas, anda catalytic compound containing a sulfur component and an alkali metalor ammonium ion component, at conversion conditions including atemperature of about 200C. to about 375C. and a pressure sufficient tomaintain at least a portion of the water as a liquid phase, andrecovering the hydrocarbonaceous product from the resulting mixture.

By employing a compound containing a sulfur component and an alkalimetal or ammonium ion component in combination with water and a reducinggas, and by utilizing temperatures and pressures in the conversionoperation whereby the water is maintained at least partially as aliquid, cellulose may be converted into liquid hydrocarbonaceous oil inhigh yields. Using the process of the present invention, hydrogen may besubstituted as the reducing gas in place of carbon monoxide, so that amixture of carbon monoxide and hydrogen, such as synthesis gas, can beeconomically employed in the present process.

DETAILED DESCRIPTION OF INVENTION Any cellulose-containing material maybe employed as the feed stock in the present process. For example,paper, cardboard, wood and other conventional vegetable matter which isnormally found in municipal refuse may be employed. It is contemplatedthat the present process may be performed using a mixture ofcellulose-containing materials with refractory materials such as metals,plastics, etc., whereby the cellulose can be liquefied and easilyseparated from the refractory solid materials by decantation. Therefractory materials may then be discarded or disposed of in anyconventional manner.

The applicable sulfur-containing and alkali metal ion-containing orammonium ion-containing catalytic compounds, include particularlysulfides and sulfurcontaining compounds capable of being catalyticallyreduced at the liquefaction conditions hereinafter described. Theapplicable compounds include, for example, alkali metal sulfides, alkalimetal sulfites, alkali metal thiosulfates, ammonium sulfide, ammoniumsulfite, ammonium thiosulfate, etc. Particular compounds which arepreferred for use as the sulfur-containing catalytic compound in thepresent process include sodium sulfide, potassium sulfide, sodiumsulfite, potassium sulfite, sodium thiosulfate, potassium thiosulfate,sodium hydrosulfide, potassium hydrosulfide, sodium hydrogen sulfite,potassium hydrogen sulfite, sodium pyrosulfite, potassium pyrosulfite,the disulfides, trisulfides, tetrasulfides, and pentasulfides of sodiumand potassium. Also preferred are the analogous ammonium compoundsincluding ammonium sulfide, ammonium hydrosulfide, ammonium sulfite,ammonium hydrogen sulfite and ammonium thiosulfate. Other suitablecompounds include lithium sulfide, lithium hydrosulfide, lithiumsulfite, rubidium sulfides, cesium sulfides, etc.; however, sodium andpotassium are particularly preferred alkali metals. Othersulfur-containing and alkali metal ionor ammonium ion-containingcompounds may be employed but not necessarily with equivalent results.Oxysulfur compounds are particularly preferred in the present process.

The reducing gas employed in the present process may be pure hydrogen orpure carbon monoxide. A mixture of these gases is also suitable. Thereducing gas may be commingled with one or more gases or vapors whichare relatively inert in the conversion operation, including nitrogen,carbon dioxide, etc. One convenient, suitable source of the reducing gasis a synthesis gas produced by reaction of carbon or hydrocarbons withsteam to produce carbon monoxide and hydrogen. A variety of methods forproducing a synthesis gas suitable for use in the present process arewell known in the art.

Conversion conditions, in the present process, include a temperature ofabout 200C. to about 375C. and a pressure at least sufficient to providea liquid water phase at the desired temperature. For example,

in an operation wherein it is desired to maintain a temperature of about200C, a pressure of at least about 20 atmospheres is maintained atconversion conditions. In high temperature operations, e.g., 350375C., apressure of about l35 atmospheres to about 220 atmospheres or more ismaintained. In the temperature range between about 200C. and about300C., the primary utility of the process of the present invention is inthe reduction of the volume of municipal refuse. At this temperaturerange, the oil produced from cellulose is heavy and approximately of thesame consistency as a crude oil. At higher temperature operations,between about 300C. and about 375C., the oil produced is lighter and maybe used directly as a feed stock to provide petrochemicals, etc.,without the necessity of further processing, as may be necessary inorder to utilize the oil obtained at lower temperature operation.

The amount of water employed in the present process in contact with thecellulose at conversion conditions is between about wt.% and about 1,000wt.% based on the amount of cellulose to be converted. Good results areobtained when the amount of water is between about 50 wt.% and about 200wt.% of the cellulose. The amount of the sulfurcontaining catalyticcompound utilized in contact with the cellulose is sufficient to providea concentration of about 10 wt.% to about 100 wt.% based on thecellulose. A concentration of about 25 wt.% to about 75 wt.% isparticularly preferred. The sulfur-containing compound may convenientlybe employed as an aqueous solution of, for example, sodium thiosulfateor ammonium thiosulfate in the water employed. When this method isutilized, it is preferred to maintain a concentration of about 10 wt.%or more of the sulfur-containing compound in solution in the water. Thesuperatmospheric pressures employed at conversion conditions in thepresent process may be wholly supplied by the reducing gas, or may besupplied, in part, by inert gases, water vapor, etc. In any case, thepartial pressure of the reducing gas is maintained at least about l0% ofthe total pressure. The amount of the reducing gas employed is generallyabout 0.5 standard cubic feet (SCF) to about 175 SCF per pound ofcellulose in the matter to be processed. Preferably the amount of thereducing gas utilized is about SCF to about 75 SCF per pound ofcellulose.

The process of the present invention may be performed in a batch-typeoperation or a continuous-type operation. When a batch-type operation isutilized, fixed amounts of the cellulose-containing material, water, thesulfur-containing catalytic compound and the reducing gas are charged toa suitable reactor such as an autoclave. The reactants are contacted inthe reactor for a period of time sufficient to produce the conversion ofthe cellulose to the normally liquid oil and then the mixture in thereactor is withdrawn and the desired liquid hydrocarbonaceous productsare separated from the any remaining solids and water and recovered. Asuitable contact time in a batch-type operation is about 30 minutes toabout 300 minutes, preferably about 60 minutes to about 200 minutes. Ina continuous operation, the cellulose-containing material, water, thesulfur-containing compound and the reducing gas are continuously chargedto a suitable reactor capable of internal agitation and contactedtherein. The mixture of the hydrocarbonaceous product, water, reducinggas and any remaining solids, is continuously withdrawn from the reactorand the desired hydrocarbonaceous product is separated and recovered. Asuitable liquid hourly space velocity in a continuous-type operation(volume of the reactor divided by the total volume ofcellulose-containing materials, water, and reducing gas charged perhour) of about 0.1 to about 1 may be employed, and a liquid hourly spacevelocity of about 0.25 to about 0.5 is particularly preferred. Thereactor utilized in the present process may be any suitable vessel whichcan maintain the cellulose-containing materials, water and reducing gasat the desired temperature and pressure in order to provide sufficientconversion. For example, a conventional rocking autoclave is a suitablereactor for use in a batch-type operation. A variety of suitable vesselsfor use as the reactor are known in the art. Preferably, the reactorincludes some means for admixing the cellulose-containing materials withthe water and reducing gas by stirring or other agitation.

The mixture recovered after the conversion operation, in addition to thedesired liquid hydrocarbonaceous product will also contain water, whichwill generally be in a separate phase from the hydrocarbonaceousproduct. Thus, the hydrocarbonaceous product may conveniently beseparated from the water and from any remaining solid materials such asmetals, plastics, etc., by simple mechanical separation of the solidsand the water. The water phase thus recovered may be recirculated to theliquefaction step for further use. Similarly, any reducing gas which isnot consumed during the conversion operation may be recovered andrecirculated to the reactor. The water phase recovered from theoperation contains some water-soluble organic materials and may alsocontain unconsumed sulfur-containing compound. The water may beevaporated leaving behind an organic material which is useful as anagricultural fertilizer.

The following illustrative embodiments are presented in order todemonstrate particular applications of the process of the presentinvention. The illustrations are presented for the purpose ofexemplification and contrast with prior art only, and are not intendedas limitations on the generally broad scope of the invention. Thoseskilled in the art will recognize from the foregoing and from theillustrations hereinafter presented that many variations and embodimentswithin the scope of the present invention are apparent.

ILLUSTRATIVE EMBODIMENT I In order to illustrate the process of thepresent invention, the conversion of commercially available paper towelsto a liquid hydrocarbonaceous oil is undertaken. One hundred grams ofcommercial paper towel is placed on 850 cc. rocking autoclave. 275 cc.of water and 30 grams of (NI- 0 8 0 are also placed in the autoclave.The autoclave is sealed and sufficient carbon monoxide is charged toprovide atmospheres carbon monoxide pressure in the autoclave. Thecontents of the autoclave are then heated to a temperature of 300C. andagitated at this temperature for 4 hours. The autoclave is then cooledto room temperature and excess pressure is released. The liquid contentsof the autoclave are removed and are observed to comprise a water phaseand an oil phase. The oil phase is decanted to separate it from thewater phase and is recovered as the product of the operation. The oilphase is analyzed and found to contain wt.% carbon and 9 wt.% hydrogen.

ILLUSTRATIVE EMBODIMENT II One hundred grams of commercial paper towelsis placed in the 850 cc. autoclave with 200 grams of water and 30 gramsof Na S O The autoclave is sealed and sufficient hydrogen is charged toprovide 70 atmospheres hydrogen pressure. The contents of the autoclaveare then heated to 300C. and agitated at that temperature for 4 hours.The autoclave is then cooled to room temperature and excess pressure isreleased. The liquid contents of the autoclave are then removed, and thehydrocarbonaceous oil product is separated from water by decantation andrecovered. In order to demonstrate the advantages of the presentprocess, the same procedure is followed using NaHCO known to prior artas a catalyst effective with carbon monoxide and water. One hundredgrams of paper towel, 200 grams of water and 30 grams of NaI-lCO areplaced in the 850 cc. autoclave. The autoclave is sealed and sufficienthydrogen is charged to provide 70 atmospheres hydrogen pressure. Thecontents of the autoclave are then heated to 300C. and agitated for 4hours. The autoclave is then cooled to room temperature and excesspressure is released. When the liquid contents of the autoclave areremoved and examined, no oil phase is observed to be present, indicatingcomplete lack of conversion of the towel to a hydrocarbonaceous liquid.Thus, NaHCO is not a catalyst when using hydrogen as the reducing gas.

ILLUSTRATIVE EMBODIMENT III One hundred grams of commercial paper towel,200 grams of water and 30 grams of Na s are placed in the 850 cc.autoclave. The autoclave is sealed and sufficient carbon monoxide isintroduced to provide 35 atmospheres carbon monoxide pressure.Sufficient hydrogen is then charged to provide a hydrogen pressure of 35atmospheres and a total pressure of 70 atmospheres. The contents of theautoclave are heated to 300C. and agitated for 4 hours. The autoclave isthen cooled to room temperature and excess pressure is released. Theliquid contents of the autoclave are removed and observed to comprise anoil phase and a water phase. The oil phase is separated by decantationand recovered as the hydrocarbonaceous product of the operation.

ILLUSTRATIVE EMBODIMENT IV One hundred grams of commercial paper towel,200 grams of water and 30 grams of Nal-ISO are placed in the 850 cc.autoclave. The autoclave is sealed and sufficient carbon monoxide andhydrogen are introduced to provide 35 atmospheres partial pressure foreach gas and a total pressure of 70 atmospheres. The contents of theautoclave are heated to 300C. and agitated at that temperature for 4hours. The autoclave is then cooled to room temperature and excesspressure is released. The liquid contents of the autoclave are removedand are observed to comprise a water phase and an oil phase. The oilphase is separated by decantation and recovered as the product of theprocess.

As shown by the foregoing description and illustrations, the process ofthe present invention provides a novel and superior method forconverting cellulose into a liquid hydrocarbonaceous oil which may beemployed as a fuel or as a feed stock to provide valuable chemicalderivatives. It is also apparent that the present invention provides aparticularly useful method for converting cellulose in that hydrogen gasmay be employed in place of, or in combination with, carbon monoxide asthe reducing gas in the present process. This is in contrast to priorart processes utilizing water and a reducing gas in which only carbonmonoxide has been found to be effective as a reducing gas. Further, itis clear that the present invention provides a valuable method forradically reducing the volume of municipal refuse by converting thecellulose-containing components of such refuse to a valuablehydrocarbonaceous product which can easily be separated from solid,unconverted components of the refuse and can be used as a fuel orfurther converted, while the unconverted refuse is substantially reducedin volume, facilitating disposal.

I claim as my invention:

1. A process for converting cellulose to a normally liquidhydrocarbonaceous product which comprises contacting paper with water,"areducing gas a catalytic compound selected from the group consisting ofalkali metal and ammonium sulfides, sulfites and thiosulfates atconversion conditions including a temperature of about 200C. to about375C. and a pressure sufficient to maintain at least a portion of thewater as a liquid phase, and recovering the hydrocarbonaceous productfrom the resulting mixture.

2. A process according to claim 1 wherein said reducing gas compriseshydrogen.

3. A process according to claim 1 wherein said reducing gas comprisescarbon monoxide.

4. A process according to claim 1 wherein said catalytic compound is analkali metal sulfide.

5. A process according to claim 1 wherein said catalytic compound is analkali metal sulfite.

6. A process according to claim 1 wherein said catalytic compound is analkali metal thiosulfate.

7. A process according to claim 1 wherein said alkali metal is selectedfrom sodium and potassium.

8. A process according to claim 1 wherein said catalytic compound isselected from ammonium sulfide,

ammonium sulfite and ammonium thiosulfate.

2. A process according to claim 1 wherein said reducing gas comprises hydrogen.
 3. A process according to claim 1 wherein said reducing gas comprises carbon monoxide.
 4. A process according to cLaim 1 wherein said catalytic compound is an alkali metal sulfide.
 5. A process according to claim 1 wherein said catalytic compound is an alkali metal sulfite.
 6. A process according to claim 1 wherein said catalytic compound is an alkali metal thiosulfate.
 7. A process according to claim 1 wherein said alkali metal is selected from sodium and potassium.
 8. A process according to claim 1 wherein said catalytic compound is selected from ammonium sulfide, ammonium sulfite and ammonium thiosulfate. 